Hard floor cleaning these days is done by first vacuuming the floor, followed by mopping it. Vacuuming removes the coarse dirt, while mopping removes the stains. From the state of the art many appliances, especially targeting the professional cleaning sector, are known that claim to vacuum and mop in one go. Appliances for the professional cleaning sector are usually specialized for big areas and perfectly flat floors. They rely on hard brushes and suction power to get water and dirt from the floor. Appliances for home use often use a combination of a hard brush and a squeegee nozzle. Like the appliances for the professional cleaning sector these products use the brush to remove stains from the floor and the squeegee in combination with an under-pressure to lift the dirt from the floor.
Said squeegee elements are usually realized by a flexible rubber lip that is attached to the bottom of the cleaning device and merely glides over the surface to be cleaned thereby pushing or wiping dirt particles and liquid across or off the surface to be cleaned. An under-pressure, usually generated by a vacuum aggregate, is used to ingest the collected dirt particles and liquid.
A squeegee that may be used in cleaning systems is, for example, known from US 20030028995 A1. A vacuum cleaner of the prior art that uses a combination of a rotating brush and a squeegee is known from U.S. Pat. No. 4,864,682 A. This vacuum cleaner comprises a self-adjusting wiper strip assembly that automatically adjusts for the type of floor surface on which the vacuum cleaner is being used. The assembly used therein requires a high suction power in order to receive a satisfactory cleaning result. The brush which is used in this vacuum cleaner is an agitator (also denoted as adjutator) with stiff brush hairs to agitate the floor, e.g. a carpet. These stiff hairs show a rather good scrubbing effect, which enable to use the brush particularly for removing stains. However, the performance on drying the floor is rather low, since such an agitator is not able to lift liquid from the floor.
Vacuum and mop in one go devices known from the prior art often use brush elements that are actively sprayed with water or a cleaning rinse in order to improve the removal of stains. Such devices usually use a double squeegee element having two squeegees that are arranged on one side of the brush, as this is exemplarily shown in the attached FIG. 15. An additional vacuum source generates a suction in a channel between said double squeegee arrangement in order to remove the cleaning water from the floor again.
However, in order to remove the actively sprayed cleaning water from the floor again these devices always have to be moved in a forward direction in which the brush is, seen in the direction of the device movement, located in front of the double squeegee arrangement. Moving the device in an opposite backward direction would leave the floor wet, since the cleaning water, which is dispersed with the brush, is not removed by the squeegees in this backward stroke.
To get a good cleaning result in a forward as well as in a backward stroke of the device known cleaning devices are therefore provided with a double squeegee nozzle at both sides of the brush. U.S. Pat. No. 4,817,233 A shows a device of this type. Even though such double squeegee arrangements on both sides of the brush show good cleaning results, the nozzle of these devices become fairly bulky. This again results in a non-satisfying, limited work capability. Especially in household appliances where often narrow corners need to be cleaned, such bulky nozzles are, due to their limited liberty of action, uncomfortable to use.
Besides that, the use of double squeegee arrangements as shown in the attached FIG. 15 and in U.S. Pat. No. 4,817,233 A has several further disadvantages. Due to the constant contact of the squeegees with the floor during the movement of the device, such double squeegees may generate a high scratch load to the floor. Especially when the double squeegee arrangements are used on each side of the brush, this will lead to an increased risk of inducing scratches on the floor. Furthermore, such squeegee arrangements include the disadvantage that they are not open for coarse dirt like e.g. hairs or peanuts, since coarse dirt is often entangled within the squeegees or is pushed away from the squeegees, and is thus not able to enter the suction inlet. Apart from that such double squeegee nozzles are hard to clean and do not have the ability to clean themselves.
Independent of the type of wet cleaning device it is one of the major challenges to obtain a uniform cleaning behavior independent of the movement direction of the nozzle. Especially in single-brush-single-squeegee solutions of the prior art this is, however, not the case. If the nozzle is moved in the forward direction in which the brush is, seen in the direction of the device movement, located in front of the squeegee, the squeegee more or less wipes off all liquid from the floor. Hence, a good drying effect is achieved. If the nozzle is, however, moved in the opposite backward direction the floor is most of the times left wet, since the cleaning water, which is dispersed with the brush, is not removed from the squeegee in this backward stroke. For a single-brush-single-squeegee solution this results in the fact that a delicate balance between the drying performance of the rotating brush and the drying performance of the squeegee is required.
Besides this problem the squeegee itself needs to be extremely abrasion and chemically resistant to maintain the initial performance over the lifetime of the appliance.
U.S. Pat. No. 5,221,828 A discloses a heated wiper blade with a conductive elastomer body and a pair of electrodes along each side of the body.
Applicant's non-prepublished applications WO/2013/027140 and WO/2013/027164 describe cleaning devices comprising a brush and a squeegee element.